In many manufacturing systems today, computers are used throughout the process to aid in the design and manufacturing of components, sub-assemblies and major assemblies. In this regard, computer-aided design (CAD) systems help component designers prepare drawings, specifications, parts lists, and other design-related elements using computer programs that are graphic and calculation intensive. In modem CAD systems, end products are designed by geometrically modeling the component in three-dimensions (3D) with a CAD computer program to obtain a component definition for the components, sub-assemblies and major installations.
Designing and developing complex 3D CAD models for many modem end products is a powerful but expensive and intricate process. In the manufacturing industry, component performance and design constraints are balanced against manufacturing capability and cost. Manufactures expend large amounts of effort and resources balancing these issues. A key product of this enterprise wide effort is the 3D CAD models of the components, sub-assemblies, and major assemblies including their respective predefined dimensional tolerances. The bulk of the manufacturing and assembly process revolves around efficiently achieving the constraints defined in and between CAD models of the components and assemblies.
Currently, modem manufacturers expend a significant percentage of their resources to develop and refine 3D CAD models for each component and assembly. Engineers must then create two-dimensional (2D) drawings to detail, dimension and tolerance component features and assembly configurations. This process defines the 2D Drawing as the configuration control and the “authority for manufacturing”. This process generates a significant duplication of effort because a series of 2D perspectives of the components have to be created and, thereafter, the tolerances have to be assigned and detailed on a 2D drawing. Thus, it would be desirable to a develop system that works directly with the nominal 3D CAD models and their tolerances to reduce the development and maintenance of conventional component design.
In many modern manufacturing systems, after a component has been designed, the manufacturing process of the component is defined, typically utilizing a computer-aided manufacturing (CAM) system, which generally includes the processes of tool and fixture design, numerical control (NC) programming, computer-aided process planning and production planning and scheduling. After defining and drafting the product, conventional manufacturing techniques are used for assembling components to produce sub-assemblies and installations. Traditionally this process has relied on fixtured tooling techniques utilizing floor assembly jigs and templates that temporarily fasten sub-assemblies and installations together to locate the components relative to pre-defined engineering requirements. This traditional tooling concept usually requires at least one primary assembly tool for each sub-assembly produced, and movement of the components from tool to tool for manufacturing operations as they are built up.
While the tooling is intended to accurately reflect the original engineering design of the end product, there are many steps between the original CAD design of the components, sub-assemblies, and major assemblies that comprise the end product and the final manufacture of the tool. It is not unusual that the tool as finally manufactured produces components, sub-assemblies, and major assemblies that are outside of the dimensional tolerances of the original CAD design and, more seriously, the tool can become out of tolerance from typical hard use it receives in the factory. Dimensional variations between the CAD design and the as-produced production components and assembly can be introduced through various means, including:    (1) Nominal product plus or minus CAD tolerances verses as-built components;    (2) Free state verses restrained component condition (i.e., clamped versus unclamped);    (3) Manufacturing process assembly variation; and    (4) High interference fastener induced assembly distortion.
Moreover, dimensional variations caused by temperature changes between the tools, which are typically fabricated from steel, and the production components, which are typically fabricated from aluminum, can produce a tolerance variation. Also, hand drilling of the component on the tool produce holes that are not perfectly round when the drill is presented to the component at a slightly non-perpendicular angle to the component, or when the drill is plunged into the component with a motion that is not perfectly linear. Components can shift out of their intended position when they are riveted in non-round holes, and the non uniform hole-to-rivet interference in a non-round hole lacks the strength and fatigue durability of round holes. The tolerance buildup on the assembly as it is moved from tool to tool can result in significant deviation from the original design dimensions, particularly when the components are located and fastened from the tool, unsystematically introducing manufacturing assembly variance. For example, if the manufacturing assembly sequence is random, the resulting manufacturing process growth will also be random and produce assembly variance.
Because of the disadvantages associated with hard tooling, rigorous quality control techniques are often employed in many modem manufacturing systems. For example, tools and fixtures are inspected periodically to ensure the tools meet required product functionality and configuration requirements, and will continue to produce an acceptable component over time. In this regard, Tool Routine inspections are scheduled inspection events that document variation and are used to adjust tool alignment features (e.g., Plum, Level, and Square CAMS data) on the tool to the original 3-2-1 tolerance settings specified on the tool engineering drawing. The frequency of a tool inspection is based on the historical performance (as measured to CAD nominal) of tool features using 3D data collection systems, such as the laser trackers, video grammetry, and computer-aided theodolites. The measured Cartesian point performance to the nominal CAD model values determines the routine frequency.
While tool routine inspections are an adequate quality control tool, they can require the expenditure of an unnecessarily large amount of resources, both in time and money. Thus, it would be desirable to provide a system that reduces component deviation from the original design dimensions without requiring a separate conventional tool routine inspection.